Widespread use of the Internet and electronic mail (e-mail) has left millions of personal computers (PCs) vulnerable to downloaded viruses and other types of malicious software that can destroy programs, copy and upload private documents, and perform other harmful acts, frequently without the PC operator's knowledge. The increasing popularity of downloaded programs has multiplied the problem significantly, since such programs create more opportunities to unknowingly download the malicious software.
Due to their open architecture, most PCs provide very little protection against such destructive software. It is this very openness that has made the PC platform the general-purpose solution provider that it is. Other types of computers are also vulnerable to such attacks in varying degrees, but the pervasive use of PCs has drawn much attention to the problem as it applies to PCs.
In the past, owners of copyrighted information or other intellectual property have been reluctant to allow their property to be viewed on the PC platform (books, movies, sensitive corporate documents, etc.) as the nature of the open PC platform makes the property vulnerable to mischievous software that may run in the background. Although self-replicating destructive software (viruses) attracts the most attention, copyright owners are more concerned with the illegal copying and distribution of any document that they permit to be downloaded to a computer. This is particularly true of video that is available electronically by downloading over a network such as the Internet, or service provider networks. The ease of copying downloaded video makes it easy to illicitly reproduce and forward copyrighted materials without detection of this activity by the copyright owner.